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Production Costs: Seeding Rates May Be a Place to Save

Encyclopedia Article

Palle Pedersen, Soybean Extension Agronomist
Originally published in the Iowa Soybean Review, December 2005

Corn and soybean production has never been more competitive than they are today. For many years, a 100 or 200-acre grain farm was able to feed an entire family, but that isn't the case anymore. Based on a survey from Iowa State University Extension, a farmer in Iowa in 2004 spends on average $271 per acre of soybean. About $140 (52%) is for the cost of the land, $38 (4%) for equipment, $32 (12%) for seed, $26 (10%) for fertilizer, $19 (7%) for herbicides, and $16 (6%) on other inputs. That means 45 bushels are needed to break even with an average price of $6 per bushel.

Today family farms are rare and most farms run by a full-time farmer are more like large commercial farms. Although we have 90,000 farms in Iowa, it is estimated that less than 4,000 farmers manage half the state of Iowa. Many of these farmers take advantage of the economy of scale and can spread out their fixed costs. However, the average Iowa farmer, who typically farmed 350 acres in 2004, doesn't have that advantage.

The success of a farming operation today is no longer dependent solely on maximum productivity. Production costs and management can have a big impact, too. Upon my arrival at Iowa State University in 2003, I started challenging all of our current soybean recommendations, such as row spacing, planting date, tillage practices, crop rotation, and seeding rates with production costs and management in mind.

In particular, I've spent much time analyzing our seeding rate recommendations because of the rising cost of seed. Our current seeding rate recommendations in Iowa are: 150,000, 175,000, and 200,000 seeds per acre for 30 inch, 15 inch, and drilled beans, respectively.

It is always difficult to find the exact seeding rate which will fit all farmers in Iowa. It depends on planter settings, planter depth, speed, seedbed conditions, seed quality, and tillage practices since crusting often is a problem in heavily tilled fields. We also know that soybean yield does not respond very well to seeding rates, because the plants can compensate for extra space by adding branches.

The current seeding rate recommendations were developed prior to the development of herbicide-tolerant crops where weed management was a serious issue. An increase in seeding rate was recommended to help compete with weeds and minimize yield loss from weed competition.

Now, even though we are not completely done with our research, I am confident we can reduce our current seeding rate by at least 10 percent without increasing risk or decreasing yield. We may be able to reduce it even more. The next year will tell.

In general, we just need 100,000 uniformly distributed plants per acre at harvest to maximize yield under most conditions.

However, we need to be really good farmers and managers if we start lowering our seeding rates. Timing of herbicide applications will be even more critical. Despite our ability to kill any size weed in our fields, the yield loss from weed-crop competition and the potential of weeds that will escape a sound herbicide program will be much more costly than the dollars you can save reducing your seeding rates.

Seed prices, on the other hand, have gone up because of new, unique traits with better disease resistance and grain composition. We receive varieties with these traits much faster than ever before, since seed companies are able to grow multiple crops in a single growing season in winter nurseries in South and Central America. Just look at seed catalogs from large seed companies — nearly 30% of the soybean varieties are new every year.

If you are thinking about using the seeding rate recommendations mentioned above in 2006, my advice is to run some on-farm trials in your fields with a small reduction in seeding rates to see if you can manage it. Remember to take stand counts in both the spring and fall — you will be surprised how many plants you are losing from plant-to-plant competition throughout the growing season when planting a high plant population.

With funding from the soybean checkoff and the Iowa Soybean Association, we have been collecting data from more than 30 experiments over the last three years, and we will continue in 2006 to see how we can adjust to the increase in seed prices without increasing our risk, and all the data will then be available to you.